1. Field of the Invention
The present invention relates to a vibratory plating apparatus which improves plating efficiency by vibrating a plating container to maintain a uniform concentration of metal ions in the vicinity of cathodes.
2. Description of the Prior Art
In a conventional apparatus of this kind, abrasive chips, a plating liquid and workpieces are placed in a vibratory container and an electric current is applied to the plating liquid to effect the plating of the workpieces. Since abrasive chips are disposed in the plating liquid in this apparatus, the lining on the inner surface of the plating container and the electrodes installed therein is likely to be worn in a short time and the current efficiency is low. Moreover, the plated surfaces of workpieces are easily contaminated with broken pieces of abrasive chips. Therefore, this kind of apparatus has not satisfied practical needs.
In a conventional plating apparatus using a barrel, workpieces are installed in a plating liquid in the barrel and the barrel is rotated or rocked to bring the workpieces into sliding contact with cathodes to subject the workpieces to electrodeposition. Barrel type plating apparatuses include one using an open-top bottle type barrel which is rotated while being inclined, and another one using a rectangular or cylindrical barrel having small apertures in the entire wall thereof, horizontally disposed in a plating liquid, and rotated or rocked with the plating liquid to effect the plating of the workpieces. The former is called an inclined barrel type plating apparatus and the latter a horizontal barrel type plating apparatus. In the inclined barrel type plating apparatus, the temperature and the concentration of the plating baths are frequently subject to changes, the insertion and withdrawal of workpieces cannot be easily carried out and anodes having a large surface area cannot be employed.
In the horizontal barrel type plating apparatus, an electric current flows through small apertures in the side wall of the barrel. Thus, the plating container requires a far higher voltage than the plating container used in other plating apparatuses in which workpieces are suspended in a plating liquid. As a result, a large amount of energy is consumed, and sparks jump across the contacts of cathode lead wires and workpieces so that the surfaces of workpieces are burnt or have holes made therein by burning. In addition, the power source and other parts will often be damaged and the plating operation cannot be conducted smoothly in many cases.
Plating with 3-4.mu. of nickel cannot be carried out efficiently in the horizontal barrel type plating apparatus or it usually requires 60-90 minutes of electrodeposition even if the diameter of apertures in the side wall of the plating barrel are enlarged. In addition, the amount of plating liquid removed from the plating barrel in this apparatus is larger than that in a widely used plating method carried out with workpieces suspended in a plating liquid. This causes the composition of the plating bath to be changed. In other words, quality control cannot be carried out easily. This large amount of plating liquid removed from the plating barrel has caused troubles in the treatment of the waste water for preventing the occurrence of environmental pollution, and has adversely affected the economy of the plating process.
These conventional plating apparatuses have many other drawbacks than those described above. They have a low productivity and require a large floor space. Consequently, the quantity and dimensions of workpieces to be plated are limited. In fact, the conventional barrel type plating apparatuses have many problems yet to be solved including the abovementioned problem of treating waste water. Namely, in a conventional barrel type plating apparatus, the plating of workpieces cannot be satisfactorily carried out unless they are soaked completely in a large amount of plating liquid which is rotated or rocked. Moreover, the plated layer on the workpieces is not a uniform thickness at each part of their surfaces because of unsufficient agitation of the plating liquid.